With the increase in residential broadband connections, the use of packet-based systems for voice communications has increased as well. One popular communications system is known as Voice over Internet Protocol (VoIP), which enables the routing of voice conversations over the Internet or other Internet Protocol (IP) networks.
One conventional VoIP implementation utilizes an analog telephone adapter (ATA), which is a device used to connect one or more standard analog telephones to a VoIP network. The ATA typically includes an Ethernet port for connection with a local area network (LAN) and a RJ-111 telephone port, into which users can plug a standard analog telephone. ATA devices typically use the SIP protocol, which is a standard for initiating, modifying, and terminating an interactive user session involving multimedia elements such as video, voice, and instant messaging. The ATA may be implemented as a standalone, dedicated ATA device, which can be connected to the Ethernet port on a router, or may be incorporated into a multi-function device, such as a residential gateway device, which includes a modem, router, and ATA. Each ATA is configured to support a predefined number of VoIP endpoints (typically one or two endpoints).
One disadvantage of conventional VoIP implementations is that all telephone devices (such as conventional analog telephones or fax machines) must be directly connected to the ATA. It is possible to connect multiple telephone devices to a single ATA by providing the ATA with multiple RJ-111 ports, or by connecting the ATA to a conventional cordless telephone base station having multiple handsets. However, a single ATA can only be used to terminate a predetermined limited number of telephone calls. Thus, if two analog telephones are connected to an ATA that only supports a single VoIP endpoint, only one of the telephones can be used at any given moment. Even if other ATAs are available on the same LAN and are not being used, the telephones connected to the first ATA cannot be used.
In other ATA implementations, the ATA may be combined with a telephone handset to provide a single integrated telephony device. Thus, the handset can have its own dedicated VoIP endpoint, network interface (such as, e.g., an Ethernet port or a wireless IEEE 802.11 interface), and audio subsystem (e.g., microphone and speaker). If multiple handsets are provided in a LAN, each handset is capable of terminating VoIP calls, thereby making all of the handsets simultaneously available to make telephone calls. A disadvantage of this arrangement is that the ATA functionality requires a significant amount of processing power to perform the necessary CODEC (coder-decoder) processes to digitize and compress the audio signal, and to encapsulate that signal into IP packets. This can dramatically increase the cost of each handset. In addition, the high power consumption of the ATA circuitry limits the amount of battery life available for wireless handset implementations.
Accordingly, there is a need for an improved packet-based communications system that enables ATA services to be more efficiently utilized in a network.